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  #1  
Old 14th September 2012
Kind of Blue Kind of Blue is offline
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Default Random Stalling at Idle + Uneven Idle, Throttle Body?

After a turbo rebuild I was having a stuttering and stalling out problem. Long story short, I've replaced the CPS, O2#1 and the voltage regulator, as I was having voltage drops into the 11's when dropping from a rev. This was all in another thread.

Everything is running great now. No more stuttering, the engine and turbo are responsive and powerful. MPG's are good.

So the idle is still uneven with a subtle chug. The other day the CEL came on going in to work with no change in car behavior. On the way home I hammered 2nd to pass someone and the TB threw itself into Limp Home mode (with P1251 P1260 codes). I reset the TB and the ECU and it has been fine.

Today, it stalled out at a stop. No stuttering at all and the engine was cold. I was waiting for the gate to open when leaving work, just after starting the car, and it just stopped running. It immediately started and drove fine the rest of the way home with 1 stop in the trip. No CEL and runs great.

The Evap Purge valve seems to be functioning properly with steady clicks, and I gave it a cleaning today for good measure. Boost valve tests out. Vac lines have been replaced and are fine. TB has been cleaned out. DIC tests out.

Is this most likely my TB in need of replacement? What else could cause this condition? It seems these things have an acutely finite life span. Obviously, I'd like to rule out any other possibilities before doling out for a TB (a BBA reman, no doubt). Or should I just suck it up and replace it anyway, as it's outlived it's life span? It hit 144k today!
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  #2  
Old 16th September 2012
Kind of Blue Kind of Blue is offline
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So my car stalled again last night. No stuttering, just died out of reverse from a cold start. The Evap Purge is "bypassed" for testing so I know for sure that's not the problem. I've been hammering the throttle and no more CEL or Limp Home Mode.
WTF could be causing this stalling? I really don't know what to look for at this point.

Anybody? <crickets>
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Old 16th September 2012
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Try cleaning the IAC, I think you need some electronic cleaner and oil. There is a write up on how to clean it somewhere on this forum.
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Old 16th September 2012
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T7 ... he doesn't have an IAC.
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Old 16th September 2012
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Age of DIC?
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Old 17th September 2012
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Quote:
Originally Posted by BobSaabit View Post
T7 ... he doesn't have an IAC.
Ah, I didn't see the year when I replied on my iPod.
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  #7  
Old 17th September 2012
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I have to assume the DIC is the original, But then it may have been replaced at some point, I don't really know. I bought the car with ~137k on it. However it's in fine physical condition (very clean, boots are fine and no smells), and passed the spark test on each coil. I know that doesn't mean it's not going bad but it seems fine. For now anyway. No more misifre codes since I replaced the CPS.

Could a bad MAF cause all this? While I had the EVAP purge valve disconnected with the line to the TB plugged, I eventually got a p0455 (evap) and a p0101..MAF. Last year it threw a MAF code on the interstate though it didn't act any differently. I cleaned the MAF and it's been fine. However it is clearly the OE MAF and now has 144k on it. I know they're a wear part with recommended replacement at 60k intervals.

Sometimes at idle the RMP's will drop slowly over a few seconds and then boost itself back and it cycles through this behavior, it seems something air-related to me. Also at startup, the boost gauge holds at about halfway through the white. Never noticed it doing that before. Today I'm going to run with the MAF electrically disconnected to see what happens, and double check all the intercooler connections.

I encourage and welcome any other input!
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Old 17th September 2012
IanT54 IanT54 is offline
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Have you tried cleaning the TB? Sounds like classic dirty TB symptoms. It's an easy job - probably less than an hour even first time. Just remove the TB and go at the inside with a can of aerosol TB cleaner and an old toothbrush.

Careful with the retaining screws when you remount it - they require very little torque.
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Old 17th September 2012
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I cleaned it with a tooth brush last year though I didn't actually remove it to do so. The plate and intake are super clean and I gave a once-over the other day. But it is old with a lot of miles on it. The TB is currently my prime suspect, just trying to rule out everything else before I squeeze myself for a new one. The SAAB has been milking me dry this month.

Intercooler hoses are all tight. I replaced the Evap Purge Valve hoses as well since they were crackly. Double checked the turbo bypass valve and cleaned it out.

Unless anyone has any other ideas I'm going to assume that my problem is either:

1) TB,
2) MAF, or
3) DIC
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Old 17th September 2012
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Run with the MAF disconnected to rule it out or in. Borrow a known good DIC (or by a used one, always good to have a spare) to rule that in or out. If the problem still persists then look into a new TB.
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  #11  
Old 17th September 2012
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Well, triple check ALL the vac lines before you start throwing parts at it. Pull 'em off one at a time and make sure there is no rotting or any tears. Cheap and easy to do to rule that out first. Also, try cleaning and undergapping your plugs. If it is the DIC, this may improve the issue somewhat. Use plenty of dielectric grease in the boots when reinstalling them.
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Old 17th September 2012
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So I disconnected the MAF and cycled it a couple times so it threw the CEL. It idled and ran notably smoother. However it ultimately stalled out again as I was slowing to make a turn and dropped the clutch. Restarted immediately as it rolled. I made a stop and reconnected the MAF, and with the CEL still on the idling has gone back to slowly falling and quickly boosting back up. Granted the behavior is subtle as it only spans a few hundred RMS's, but it's still there.
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Old 17th September 2012
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Quote:
Originally Posted by Saaboheme View Post
Well, triple check ALL the vac lines before you start throwing parts at it. Pull 'em off one at a time and make sure there is no rotting or any tears. Cheap and easy to do to rule that out first. Also, try cleaning and undergapping your plugs. If it is the DIC, this may improve the issue somewhat. Use plenty of dielectric grease in the boots when reinstalling them.
I have checked them all but will remove them and inspect them more closely as you recomend. I replaced all the main ones just last year so they're in great condition. I've also redone the PCV system, so all those hoses and valves are new and intact. I checked the plugs a week ago or so and they are fine (NGK's). I hit them with some cleaner for good measure. Plenty of dielectric grease in the boots. I'm trying to avoid throwing parts at it, for sure.
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Old 17th September 2012
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Sounds like the MAF is showing it's age, but isn't the complete cause of the stalling issue. The CEL with the MAF disconnect is to be expected, you need to pay attention to the idling/stalling behavior and ignore the CEL. I'd move on to borrowing a good DIC if possible or picking up a cheap good used one, then you at least have one as a spare.
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Old 18th September 2012
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So as it turns out my DIC has been replaced. It has a date stamp of 0917 and is version TK3.7. This explains why it appears to be in such good condition!

So it seems narrowed down to the TB. I'm going to change the plugs for good measure and remove the TB for a thorough cleaning. I've been running Platinum 7H10's, not realizing that my car spec 's 6's. So I'm going to throw in a set of standard (BCPR) 6's.
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Old 18th September 2012
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Do you have a boost gauge T'd into the vacuum line for the MAF? I had it done this way on my car, and when I traveled to Colorado I started randomly stalling out for no reason. Removed the boost gauge from this line and solved my problem.
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Old 18th September 2012
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I'd BBC the TB.
The throttle body does many things, including the idle speed.
BBC rebuilds the TB assemblies, and they seem to have a good name.
Google BBC, eEuro, RockAuto.
First off, do the vacuum hoses..economic logic....that and they simply last not.
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Old 18th September 2012
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No extra boost gauge. Literally all vac lines have been replaced and triple checked.

Today I did three things.

1) New Plugs: 6's, gapped tight.

2) Removed Intercooler and cleaned it out with 2 cans of cleaner. TONS of oil. (From the leaky turbo before the rebuild, no doubt.)

3) Removed, cleaned and dissected the TB. Lots of oil about and some sitting in the intake manifold. Obviously getting blown up from the IC. Also I cleaned up the wiring inside - the four wires that are accessible enough, I de-soldered and shrink wrapped. The other four that run through the TB I tediously wrapped with electrical tape.

First run after all this and it seems to run much better, but time will tell. The idle started drifting again but I attribute this to the MAF. The weird thing is, after all this, for the first time ever, it's overboosting to fuel cutoff! It could be the spanky clean IC and TB/intake, together with the ECU reset, and will tame itself.
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Old 18th September 2012
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By chance do you mean BBA or is there a BBC as well? I had my SID reman'd by BBA, and they also do TB's and whatnot. That's who I was planning to go through when the time came. RockAuto has sent me parts that don't fit on more than one occasion, for both Volvo and SAAB, so I don't even bother with them anymore. One was the rear main seal for my SAAB, which of course I didn't realize did not fit until I had the tranny out on the ground. Luckily O'Reilly's had the proper seal. That was a major hose. I get most of my SAAB parts from eEuro, they're great!

I've only recently learned how many functions the T7 TB's serve, and likewise how prone they are to fail or cause problems. From what I can tell the main problem with these TB's seems to be the housing for the wiring inside drying out and cracking off, leaving 8 bare wires folded up together in close proximity. And with the pots wired in reverse parallel any sort of interference, cross talk or at worst, touching, is going to cause problems. Hopefully by having cleaned that up I've put off TB replacement until a more opportune time.

Quote:
Originally Posted by earthworm View Post
I'd BBC the TB.
The throttle body does many things, including the idle speed.
BBC rebuilds the TB assemblies, and they seem to have a good name.
Google BBC, eEuro, RockAuto.
First off, do the vacuum hoses..economic logic....that and they simply last not.
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  #20  
Old 19th September 2012
Kind of Blue Kind of Blue is offline
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Well I'm happy to report that the SAAB is now running wonderfully!

Because I'm not smart I forgot to tighten the clamp for the IC inlet hose, hence the over boosting. Now I have an even idle, full proper boost (tickles the red and holds), no stuttering, no hesitation and no stalls. Everything is responsive, smooth and powerful, as it should be, and SO much fun to drive. At risk of speaking too soon, it now seems to be running at it's best since I bought it.

Since I must speculate, I believe the TB wiring to be the main culprit, the condition caused by which was then exacerbated by the oil and oil vapor being pushed into it from the IC.
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